This invention relates to an assembly for receiving flows from a sink or other apparatus and, more particularly, to the prevention of a backflow, or back siphoning, in a fluid handling system. This apparatus, therefore, provides a connection that satisfies a minimum air-gap separation requirement.
In order to maintain sanitary conditions, plumbing and health code regulations require device drains to be individually drained with a flow passing through a minimum air space to preclude potential cross-contamination caused by fluids migrating upstream due to a downstream blockage. Traditional air-gap connection methods have commonly used a pipe-and-cup arrangement. Effluent flows through a drain, passes through a mandated air-gap into a cup, and then passes through a pipe to a remote location. This conventional set-up requires an adequate vertical distance to be available. However, in many modem commercial kitchens, most devices discharge low to the floor and preclude such a pipe-and-cup design, particularly if other equipment needs to be installed downstream of the drain. A particular item of this sort is the Big Dipper.RTM. grease separator sold by Thermaco, Inc. of Asheboro, N.C. Grease separators remove oil and grease from kitchen sink effluent so that the remaining effluent is easier to process, in compliance with many sewage district codes. The oil/grease separators have tanks with quiescent zones to permit the oil and grease to float on top of the water and be susceptible to removal. Such tanks need vertical height, which may not be available in traditional air-gap drains.
A key characteristic of many backflow prevention techniques is that they must be oriented vertically. Examples of such devices are disclosed in U.S. Pat. Nos. 3,455,324 (Bieri et al.), 5,159,958 (Sand), 5,305,778 (Traylor), and 5,678,592 (Boticki et al.), among several others. For backflow prevention, the Bieri device includes a nozzle and a diffuser that are aligned with one another and the discharge end of the nozzle is spaced from the inlet end of the diffuser to provide therebetween an air-gap through which water flows. Likewise, the Sand device prevents backflow by locating an air-gap chamber downstream of a nozzle and upstream of a conical sloped orifice. Sand is also an example of a backflow prevention technique that is combined with Venturi-type mixing devices, sometimes known as eductors.
A problem with the above-identified devices is that when the water stream flows from the drain across the air-gap to the opening, for example, as described in Sand as a conical sloped portion, there is a tendency for lateral splash-out toward the slots leading to ambient air. Attempts to prevent such splash-out include upwardly-extending tabs or radially inwardly offset transparent windows. However, it is understood that persons charged with enforcing plumbing codes find these techniques objectionable because either they are prevented from visually observing the presence of the air-gap or prevented from physically passing an object or a finger through the air-gap.
Yet another characteristic of eductor-type backflow preventers is that reasonably high water pressure is required to provide adequate downstream pressure drop to drive the eductor for satisfactory mixing.
There remains, therefore, a need in the art for a backflow prevention device that need not be oriented vertically but still maintains the mandated air-gap separation. Sometimes, vertical orientation is not practical or even possible. An assembly that is able to keep the air-gap distance and vertical dimension substantially the same would have substantial commercial utility.